Buggy code:
@ Value ( "${appl.is_url}" ) private String is_url ; public ModelAndView handleRequest ( HttpServletRequest request , HttpServletResponse response ) throws IOException , ParseException , ServletException { logger . info ( ( "***<seq2seq4repair_space>Inside<seq2seq4repair_space>Tools<seq2seq4repair_space>controller<seq2seq4repair_space>" + ( request . getParameter ( "oper" ) ) ) ) ; Calendar cal = Calendar . getInstance ( ) ; Date curTime = cal . getTime ( ) ; SimpleDateFormat sdf = new SimpleDateFormat ( "yyyy-MM-dd" ) ; Map < String , Object > myModel = new HashMap < String , Object > ( ) ; String operstr = request . getParameter ( "oper" ) ; String atype = request . getParameter ( "atype" ) ; String testid = "0" ; testid = request . getParameter ( "testid" ) ; String freq = request . getParameter ( "freq" ) ; if ( ( ( ( testid == null ) || ( testid == "" ) ) || ( testid == "null" ) ) || ( testid . equals ( "undefined" ) ) ) { testid = "0" ; } if ( ( ( ( freq == null ) || ( freq == "" ) ) || ( freq == "null" ) ) || ( freq . equals ( "undefined" ) ) ) { freq = "-1" ; } if ( operstr == null ) { logger . info ( "***<seq2seq4repair_space>error<seq2seq4repair_space>condition.<seq2seq4repair_space>operstr<seq2seq4repair_space>is<seq2seq4repair_space>null<seq2seq4repair_space>!!**" ) ; operstr = "null" ; } else { if ( operstr . contains ( "rset" ) ) { logger . info ( ( "***<seq2seq4repair_space>rset<seq2seq4repair_space>**<seq2seq4repair_space>testid<seq2seq4repair_space>" + testid ) ) ; String strfreqs = "" ; List < TestFrequency > freqlist = this . mastersservice . getFreqList ( Integer . parseInt ( testid ) ) ; for ( int i = 0 ; i < ( freqlist . size ( ) ) ; i ++ ) { if ( i == 0 ) { strfreqs = ( freqlist . get ( i ) . getFrequency ( ) ) + "" ; } else { strfreqs = ( strfreqs + "," ) + ( freqlist . get ( i ) . getFrequency ( ) ) ; } } logger . info ( ( "***<seq2seq4repair_space>strfreqs<seq2seq4repair_space>**<seq2seq4repair_space>" + strfreqs ) ) ; myModel . put ( "testid" , testid ) ; myModel . put ( "strfreqs" , strfreqs ) ; myModel . put ( "freqlist" , freqlist ) ; myModel . put ( "atype" , atype ) ; return new ModelAndView ( "reportset" , "model" , myModel ) ; } else if ( operstr . contains ( "hpolar" ) ) { logger . info ( ( "***<seq2seq4repair_space>hpolar<seq2seq4repair_space>**<seq2seq4repair_space>testid<seq2seq4repair_space>" + testid ) ) ; TestData pd = mastersservice . getTestData ( Integer . parseInt ( testid ) ) ; String ptype = pd . getPtype ( ) ; if ( ( atype . equals ( "E" ) ) && ( ptype . equals ( "L" ) ) ) { atype = mastersservice . getType ( Integer . parseInt ( testid ) ) ; } if ( ( atype . equals ( "A" ) ) && ( ptype . equals ( "L" ) ) ) { atype = "Y" ; } myModel . put ( "freqlist" , this . mastersservice . getFreqList ( Integer . parseInt ( testid ) ) ) ; myModel . put ( "testid" , testid ) ; myModel . put ( "freq" , freq ) ; myModel . put ( "atype" , atype ) ; return new ModelAndView ( "hpolar" , "model" , myModel ) ; } else if ( operstr . contains ( "db" ) ) { TestData pd = mastersservice . getTestData ( Integer . parseInt ( testid ) ) ; String ptype = pd . getPtype ( ) ; if ( ( atype . equals ( "E" ) ) && ( ptype . equals ( "L" ) ) ) { atype = mastersservice . getType ( Integer . parseInt ( testid ) ) ; } String typ = request . getParameter ( "typ" ) ; logger . info ( ( ( ( "***<seq2seq4repair_space>db<seq2seq4repair_space>**<seq2seq4repair_space>testid=<seq2seq4repair_space>" + testid ) + "<seq2seq4repair_space>atype=<seq2seq4repair_space>" ) + atype ) ) ; myModel . put ( "atype" , atype ) ; myModel . put ( "testid" , testid ) ; myModel . put ( "typ" , typ ) ; return new ModelAndView ( "xdb_bw_bs" , "model" , myModel ) ; } else if ( operstr . contains ( "ar" ) ) { String typ = request . getParameter ( "typ" ) ; logger . info ( ( "***<seq2seq4repair_space>db<seq2seq4repair_space>**<seq2seq4repair_space>testid<seq2seq4repair_space>" + testid ) ) ; myModel . put ( "testid" , testid ) ; myModel . put ( "typ" , typ ) ; myModel . put ( "atype" , atype ) ; return new ModelAndView ( "ar" , "model" , myModel ) ; } else if ( operstr . contains ( "ampphase" ) ) { logger . info ( "***<seq2seq4repair_space>ampphase<seq2seq4repair_space>**<seq2seq4repair_space>" ) ; myModel . put ( "prodlist" , mastersservice . getProductList ( ) ) ; return new ModelAndView ( "ampphaserpt" , "model" , myModel ) ; } else if ( operstr . contains ( "viewaptracking" ) ) { String maxDiff = "" ; String maxFreq = "" ; String typ = request . getParameter ( "typ" ) ; String prodseriallist = request . getParameter ( "prodseriallist" ) ; Map < String , Object > resultset = mastersservice . GetAmpPhaseValue ( prodseriallist , typ ) ; logger . info ( ( "viewaptracking<seq2seq4repair_space>prodseriallist=" + prodseriallist ) ) ; logger . info ( ( "Return<seq2seq4repair_space>out<seq2seq4repair_space>value:" + ( resultset . size ( ) ) ) ) ; if ( ( ( resultset != null ) && ( ( resultset . size ( ) ) > 0 ) ) && ( ! ( resultset . isEmpty ( ) ) ) ) { if ( ( ( resultset . get ( "maxDiff" ) ) != null ) && ( ( resultset . get ( "maxFreq" ) ) != null ) ) { <START_BUG> maxDiff = resultset . get ( "maxDiff" ) . toString ( ) ; <END_BUG> freq = resultset . get ( "maxFreq" ) . toString ( ) ; } } logger . info ( ( ( ( "***<seq2seq4repair_space>ampphase<seq2seq4repair_space>**<seq2seq4repair_space>typ<seq2seq4repair_space>" + typ ) + "<seq2seq4repair_space>prodseriallist<seq2seq4repair_space>" ) + prodseriallist ) ) ; return new ModelAndView ( new RedirectView ( ( ( ( ( ( ( ( "//birt-verdant//frameset?__report=PhaseTracking.rptdesign&type=" + typ ) + "&prodserialids=" ) + prodseriallist ) + "&maxamp=" ) + maxDiff ) + "&freq=" ) + freq ) ) ) ;

Fix:
maxDiff = "±" + ( resultset . get ( "maxDiff" ) . toString ( ) ) ;